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Self-Assembled Smectic Phases in Rod-Coil Block Copolymers
1J. T. Chen and E. L. Thomas, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. C. K. Ober and G.-p. Mao, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
Abstract:
Rod-coil block copolymers are self-assembling polymers that combine the physics of orientational ordering of rodlike polymers and the microphase separation of coil-coil block copolymers. Several new solid-state morphologies were observed in a series of anionically synthesized model poly(hexyl isocyanate-b-styrene) rod-coil diblock copolymers examined by transmission electron microscopy and selected-area electron diffraction. The rod-coils formed smectic C-like and O-like morphologies with domain sizes ranging from tens of nanometers to almost 1 micrometer. Both structural and orientational changes were found for increasing rod volume fractions. In addition, some morphologies exhibited spontaneous long-range orientational order over many tens of micrometers.